3 Answers
3

Generating prime integers and computing things modulo integers is easy with a programming language which features support for big integers. I usually use Java: it includes java.math.BigInteger, with which one can:

generate prime integers of any length;

do all basic operations, including modular reduction (mod() method);

compute modular inverses (modInverse());

compute modular exponentiations (modPow()).

For irreducible polynomials, things are more complex: Java does not offer a generic method for testing irreducibility of polynomials (or, for that matter, anything related to polynomials). I do have my own library but it is not generally available (I implemented it for a customer). However, my friend Google points out that this library appears to be fairly complete in that area.

No, the multiplicative inverses of numbers in the prime field $Z_p$ (i.e. $a$ modulo the prime number $p$). For that, you will need to use the Extended Euclidean Algorithm. Have a look at the following link to some lecture notes on how to do this. www.ijecbs.com/July2011/14.pdf
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user476Aug 15 '11 at 3:39

I know, I was just making it clear. Also, multiplicative inverses in Z_n can be computed faster using Euler's theorem and Fermat's little theorem.
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VicfredAug 15 '11 at 3:41

1

I believe that you are right. Not certain about this, as it has been a while since I last did it. Good luck!
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user476Aug 15 '11 at 3:43

@Vicfred - Oops! Sorry, gave you the wrong link before. Here's a link to the quick view of the PDF that I was referring to earlier. docs.google.com/… If you do a google search, you should be able to find the PDF.
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user476Aug 15 '11 at 3:57

It gets tricky supplying large numbers because queries are limited to 200 characters. Also you can't store variables and use them in subsequent queries. That is why using the actual applications is better. (For example, the last query above would simply be PowerMod[a,-1,p] if you could store a and p after you generate them.)